Transmission-regulating circuits



Jully 1, 1924. MQMM O. H. LOYNES TRANSMISSION REGULATING CIRCUITS FiledJan. 26, 1921 2 Sheets-Sheet l amemtoz Z0 law $513 luon L01 Juhr n mm.Mwwm O. H. LOYINHES TRANSMI SS ION REGULAT I NG CIRCUITS Filed Jan. 263.921 2 Shams-Sheet 2 GWEN H. LOYNES, OF WOODMDGE, NEWJJERSE'Y, ASSIGNOR1'0 ERICAN TELEPHONE il TELEGRAPH COMPANY, A CORPOTION OF NEW YORK.

TNSMISSION-REGULATJING CIRCUITS.

. .Application filed January 26, 1921. Serial inc. 440,103.

To all whom it may concern:

Be it known that l[, OWEN H. LoYNEs, residing at Woodridge, in thecounty of Bergen and State of New Jersey, have invented certainImprovements in Transmission-Regulating Circuits, of which the followingis a specification.

a This invention relates to signaling circuits and more particularly tomeans for controlling the transmission equivalent of such circuits.

In general, the transmission equivalent of a circuit varies, due to anumber of causes. For example, in the case of a transmission circuit ofthe four-wire type in which a pair of separate transmission lines areemployed for transmission in opposite directions, the transmission mayvary due to causes which affect both sides of the circuit in the samemanner. For example, variations may occur in the resistance of theconductors or loading coils, or variations in the capacity, inductance,or electrical characteristics of the cable may affect the transmissionequivalent. The same holds true of variations in the potential ofrepeater batteries common to repeaters in both sides of the circuit.There are also a number of factors which affect the two sides of thecircuit diflerently,-such as variations in the structure of the repeaterbulbs, variations in the potential of the grid batteries, or accidentalvariations due to the existence of bad joints, etc. I

All of these causes may contribute to produce considerable variation inthe transmission over a circuit from time to time, thus rendering itdesirable that some means be provided whereby the transmissionequivalent may be maintained constant. lit has heretofore been proposedto control the adjustment of the transmission equivalent bydisconnecting the ends of the two transmission lines, comprising afour-wire circuit from their terminating arrangements, and theninterconnecting the ends'through loop connections which may include adustable transmission devices. The gain in the fourwire circuit thuslooped together at the ends is then increased to a maximum value so thatsingin takes place in the circuit. By gradually ecreasing thetransmission equivalent, as for example, by varying the amplification ofa repeater in the circuit, a point will be four-wire circuit arenormally looped to gether with the singing responsive relay bridgedacross the circuit when it is not 1n use.

Another object of the invention is to provide a circuit of the'characterabove set forth in which the voice operatedb'fsinging re-" sponsiverelay is bridged across the circuit at one end and the regulatingelement is located at an intermediate point in the fourwlre c1rcu1t.

Another object of the invention is to provide a regulating circuit whichis arranged to function at regular intervals, but which is so organizedthat if the circuit is busy at the time the regulating means normallyfunctions, the regulating mechanism will be maintained unoperative untilthe circuit is released, when it will proceed to correct thetransmission equivalent in the usual manner.

Another object of the invention is to provide a circuit which isarranged to give a busy indication during the period when it is beingregulated to warn the operator that she should not plug into the line.The cir-- cuit is also preferably so arranged that should the operatorplug in while it is being regulated, no harm can be done.

Another object of the invention is to provide a circuit which is soarranged as to prevent ringing current from coming back on one side ofthe circuit when ringing on the other side, 'due to the endsbeingnormally-looped together.

The arrangements for accomplishing these objects as well as otherobjects, more fully appearing hereinafter, will be clear from thefollowing description when read in connection with the accompanyingdrawing,

Figs. 1 and 2 of which, when taken together, constitute a circuitdiagram embodying a preferred form of the invention.

Referring to the drawing, apparatus is shown associated with a four-wirecircuit interconnec'ting stations A, B and C, said circuit comprisinglines LE and LW between Y connected through a balanced transformerarrangement 10 with a two-wire terminal leading to a jack J and anartificial line or network N is provided for balancing the two-wire linewhich may be associated with the jack. In a similar manner, the lines LEand LW are connected through a balanced transformer 11 with a two-wireterminal leading to a jack J which serves to connect the system with atwo-wire line. A network N is provided for balancing the two-wire linewhich may be connected to the jack. In the normal condition of thecircuit, the lines LE and LVV are disconnected fromthe balancedtransformer 10 and the two-wire terminal and are looped directlytogether over conductors 12. Re-

lays 13 and 14 are provided, however, which under proper conditions willdisconnect the lines fromconductors 12 and connect them to the balancedtransformer and two-wire terminal arrangement. Similarly at station Cthe lines LE and LW are normally looped together'over conductors 15 andrelays 16 and 17 are-provided for disconnecting the ends of the linesfrom each other and associating them with the transformer 11 and theother terminal apparatus.

At station B amplifying arrangements are provided, comprising one-wayrepeaters RE and RW, included between the line sections. These repeatersare provided with potentiometers PEand PW for controlling theiramplifications, the setting of the potentiometers being determined by anautomatic switch having wipers S, SE and SW. In order to control thesetting of the switch, a brid e connection 18 is provided at station A,t is bridge connection being associated with the conductors 12 andhaving connected therewith an amplifier R and a voice controlled relay Vof well known type. The

voice controlled relay V determines the action of the switch S by meansof a simplex circuit extending through the several stations over the twosides of one of the lines in parallel.

Further details of the apparatus will now be clear from a detaileddescription of the operation which isas follows:

An operator at the station A, desiring to establish a connection with atwo-wire line at the station C, will plug into the jack J therebenergizing the relay 19, which in turn 0 oses a circuit of relay 20.Relay 20 completes a circuit from ground over its upper contact, uppernormal contact of relay 21 and through the windings of relays 13 and 1-1'to battery. Relays 13 and 14-, upon being energized, disconnect thelines LE .and LW from the loop through the circuit 12 and connect saidlines through the balanced transformer 10 with the twowire terminalleading to the jack J so that the circuit, so far as station Ais-concerned, is in condition for carrying on a conversation. Theoperator at station A then applies ringing current to the talkingconductors of the two wire-terminal, thereby operating the ringingresponsive relay 22. Relay 22, operating in response to the ringingcurrent applied to the two-wire terminal, opens the circuit of a slowrelease relay 23, which in turn closes a circuit through relays 24 and25. Relay 25' disconnects the line LVV from the bridge across themidpoints of the balanced transformer 10 to prevent the ringing currentfrom actuating the ringing relay 26, associated with the line LVV. Relay24 completes a circuit for the ringing relay 27, which connects ringingcurrent over its front contacts to the terminals of the line LE, so thatthe ringing current is transmitted over the lines LE and LE,tostation C.The ringing current thus transmitted actuates the relay 28 at station Cto open the circuit of the slow release relay 29. Relay 29, uponreleasing its armature, completes a circuit from'ground over the innerleft hand back contact of relay 30 through the winding of relay 31 andthrough the winding of relay 32 to battery. Relay 32 disconnects theline LE from the bridge connected across the midpointsof the windings ofthe transformer 11, thereby preventing the ringing current fromactuating the ringing responsive relay 33. Relay3l completes a circuitthrough the windings of relays 34 and 35, the former of which opens theconnection 15 between the lines'LE and LW to prevent the ringing currentfrom being transmitted back over the lines LlV and LVV to station A.Relay 35 over its front contacts applies ringing current to the terminaldr (not shown). The operator at station C, in response to the ringlngsignal thus transmitted, will plug into the jack J thereby operating therelay 64. Relay 34 completes a circuit from ground over its frontcontact over'the left-hand back contact of relay 30 and through thewindings of relays 16 and 17 to battery. Relays 16 and 17 disconnect thelines LE and LW from the loop through the circuit 15, and connect thelines directly to the transformer 11 and terminal equip ment so'that theentire circuit from station A to station C is now in condition to carryon a conversation the usual manner.

In order to adjust the transmission equivalent of the circuit thusdescribed at peaaaaaca riodic intervals, a contact 35 is provided atstation A. This contact may be operated b a clock or other suitablemechanism whic may be arranged to close the contact, for example, everyhalf hour. Contact 35, when operated, completes a circuit through theslow release relay 36. Relay 36 at its lower front" contact completes acircuit from battery' over the lower back contact ofrelay 20 overconductor 37 and through the winding of relay 21 and resistance 38 toground. This circuit will not be completed if the fourwire circuit isbusy at the moment when the key 35 is operated, since the relay 20 isactuated when the circuit is busy, thereby 1 contact opens the circuitof relays 13 and 14 to prevent any possibility of these relays beingactuated to disconnect the lines LE and LW from the loop connection 12,should an operator plug into the jack J At its remaining front contact,relay 21 completes a circuit for the relay 39. ltelay 39, at its lowerfront contact, connects battery to a busy signal (not shown) and at itsupper contact opens the circuit controlled by the ringing responsiverelay 26 through the slow release relay 40. At its middle front contactrelay 39 connects a Morse battery to a simplex circuit over conductor41, the two sides of the line LW in parallel through the windin of relay42 at station 18 over the two sides 0% the line LWt in parallel andthrough the windin of relay 43 at station-"C to ground. Re ays 42 and 43are operated over the circuit just traced, the latter functioning tocomplete the. circuit of the relay 30 which at its right hand contactconnects battery through a resistance 44 to the sleeve wire to put abusy test on the sleeve. At its extreme left hand contact relay 30 opensthe circuit of the relays 16 and 17 to prevent the disconnection of thelines LE and LW' from the loop through the circuit 15 in case anoperator should plug in the jack J At its milddle contact relay 30 opensthe circuit of relays 31 and 32 to pre vent the transmission of a falseringing sig naldue to any possible actuation of the relay 28. a

At station 18 the actuation of the relay 42 completes a circuit fromground. over its left hand front contact over conductor 45 to point 46,and thence over the right hand back contact of relay 47 through thewinding of relay 48: to battery. A parallel connection extends frompoint46 over the normal contact of relay 49 over the lower back' contact ofstepping magnet SM' to battery. Relay 48 upon being actuated, shiftsthe-"potentiometer connections so that they are 'no lIgE'eP-tOlltlOllfldby the switch arms SE and these conditions, the four-wire circuit whichis looped together at its ends, begins to sing or howl. Returning forthe moment to the stepping magnet SM the said magnet is operated, overthe circuit previously traced through its Winding and intermittentlyinterrupts its own circuit, thereby stepping the switch wipers S, SE andSW from the position of a j viously set, to the position for maximumgain, at which point connection will be established from ground over thewiper S, over the conductor 59 and thence in parallel .through thewindings of relays 47 and 49 to battery. Relay 49 opens a circuit tracedfor the steppin magnet S lay 49 at its outer right hand contact opens acircuit of the rela 48, which releases to restore the control 0 ,thepotentiometers PE and PW to the switch wipers SE and SW'. At its innerright hand front contact, relay 47 looks up over conductor 45 so thatthe fieviously but are set tormaximum gain. lUnder and re-.

ustment in which they were precircuit is now controlled by the relay 42.At

its left hand front contact, relay 47 completes a circuit through theinterrupter 50 and the winding of relay 51. Relay 51 is thereforeintermittently energized and at its front contact controls theenergization of the stepping magnet SM, which new continues to step theswitch wipers step by step to graduall reduce the gain of the amplifiersRE an RW. As soon as the circuit began to sing upon the energization ofthe relay 48 at station B and during the continuance of the singin whilethe potentiometers are being adjuste the singing tone was impressedthrough the circuit 18 and amplifier R upon the voice operated relay V,The armature of this relay is normally adjusted to maintain the circuitof a slow release relay 52 closed. The chat- .tering of the armature ofrelay V reduces the current through the relay 52, which is deenergized.At its upper back contact relay 52 completes a circuit for relay 53 andthe circuit remains in this condition so long as the singing continues.When, however, the stepping of the switch at the station B has reducedthe gain of the repeaters until the four-wire circuit has a zerotransmission equivalent, the singing ceases and the voice 0 erated relayV assumes its normal conditron, so that the circuit through the slowrelease relay 52 is again closed. At its upper contact relay 52 opens acircuit of the slow release relay 53, but before the armature of signaldisconnecting the Morse battery from at station B and relay 43 atstation 0. .Re

' either end the simplex circuit over the conductor 41 and causing thedeenergization of relay 42 lay 43 at station C opens a circuit of relay30, thereby removing the busy test from the sleeve of jack J andrestoring the apparatus at station Cto normal; Relay 42 at station B, byremoving the ground from the point 46, causes the release of relay 47,which opens the impulse circuit for the stepping magnet SM, thusbringing the switch wipers to rest inthe position to which they havebeen adjusted. Duringthe stepping of the switches, the relay 49 waslocked up over themiddle locking contact of relay 47 to hold open theoriginal stepping circuit of the magnet SM. The disconnection of theground from point 46 therefore, releases relay 49 at the same time thatrelay 47 is deenergized.

It will be observed that during the process of adjustment of thetransmission equivalent just described, relay 21 at station A and relay30 at station C are maintained energized. The relay 21 through the relay39, as previously described, controls the busy signal and the relay 31applies abusy test to the jack J Operators are therefore warned againstinterfering with the process of adjustment of the circuit by beingapprised that the circuit is busy. Should an operator plug into of thecircuit, however, the process of adjustment will not be interfered withsince relays 21 and 30 hold open th e'circuits of relays 13 and 14 atstation A and relays 16 and 17 at. station O,.thereby preventing theopenin of the loop.

Should the condition of the circuit at any time become such that acontinuous singing or howling takes place,

this fact alone will be sufficient to institute the operations necessaryto adjust a circuit without the actuation of the time controlled key 35.For example, when the'apparatus associated with the four-wire circuit isin normal condition, a singing oscillation transmitted over the circuitwill operate the voice relay V in the manner already described, to causethe release of the slow release relay 52. The relay 52 at its upper backcontact completes a circuit for relay 53, as already described; at itsupper front contact relay 52 when energized, maintains the circuit ofslow release relay 54 closed and relay 54 in turn'maintains the circuitof a slow release relay 55 closed. Therelease of relay 52 is thereforefollowed after an interval, by the release of relay 54, which in turn isfollowed after another interval by the release of relay 55. Relay 55closes a circuit from battery over the lower back contact of relay 52,back contact of relay 55 and over conductor 37 through the winding ofrelay 21 and through resistance 38 to ground. As soon as the relay 21 isenergized over this path the succeeding operations incident toadjustment of the circuit, take place in exactly the same manner as hasbeen previously described. The purpose of the chain of slow releaserelays 52, 54 and 55 is to prevent the actuation of the relay 21 underthe conditions just described, where the circuit picks up a temporarynoise or howl by induction from some external circuit, thus preventingan unnecessary adjustment of the switches.

If, after the process of adjustment has started and the switch wipers atstation B are being rotated, the conductors of the four-wire circuitshould be opened at any point, as for example, by an operator at atestboard, the singing would at once cease and the rotation of theswitch would be stopped in the samemanner as occurs when singing ceasesbecause of proper adjustment of the circuit. As soon as the circuit isclosed again, however, singing will com mence owing to the fact that thefour-wire circuit is out of adjustment and the chain of slow releaserelays 52, 54 and 55 will again be set in operation to negotiate theprocess of adjustment anew, so that it can continue from the point atwhich it was interrupted.

Itwill be obvious that the general principles herein disclosed may beembodied in many other organizations widely different from thoseillustrated, without departing fronr the spirit of the invention asdefined in the following claims.

What is claimed is:

1. A four-wire circuit comprising two lines for transmitting in oppositedirections, means normally looping the lines together at their ends,terminal arrangements for connecting said lines with terminal two wirelines, and means responsive to the connection of said two wire lineswith said terminating-arrangements for opening said 100 connections andconnecting the l1nes 0f the naeaaea from the means for looping the endsof said lines together, and for connecting said pair of lines with saidhybrid coil.

3. A four-wire circuit comprising a pair of transmission lines fortransmitting in. opposite directionsf'me ans normally looping the endsof said lines together, terminal arrangements whereby the ends of saidpair of lines may be'associated with terminal two wire lines, meanswhereby in response to the establishment of atransmission connectionwith one of said terminal arrangements, the corresponding ends of saidpair of lines are disconnected from said means for looping the endsthereof together, and are associated with said terminal arrangements,means for transmitting ringing current over one of the lines to theopposite end thereof,

and means responsive to ringing current,

thus transmitted, for opening the means for looping the opposite'ends ofsaid pair of lines together, in order to prevent the ringing currentfrom being transmitted back over the other line.

at. A four-wire circuit comprising a pair of transmission lines fortransmittin in o posite directions, means for looping t e en s of saidlines together, terminal arrangements rangements including signalingmeans for calling the attention of an operator, means for associatingthe ends of said lines with terminal two-wire lines, said terminalarresponsive to the establishment of a connection with the terminatingarrangement associated with one end of the lines for dis connectingthe-ends of said lines from said means for looping the ends together,and connecting the lines to the terminating arrangement associatedtherewith, means for transmitting ringing currentover one of the linesto the distant end thereof, means at the distant end of; said lineresponsive to said ringing current for opening the means for looping theopposite ends of the-lines together, to prevent the ringing current frombeing transmitted back in the opposite direction over the other line,and means whereby the ringing current will actuate the signaling meansfor calling the attention of an operator.

5."A four-wire circuit comprising a pair of transmission lines fortransmitting in opposite directions, means for normally looping the endsof said lines together, to form a circuit' which will sing when the gainexceeds the loss, terminating arrangements for said lines, means wherebywhen a transmission circuit is extended over said lines, the ends ofsaid lines will be disconnected from said means for looping the endstogether, and connected with said terminating arran ments, and devicesassociated with one oft e means for loopin the ends of said linestogether for respon ing to the singing ofthe circuit.

6; A four-wire circuit comprising a pair .of transmission lines fortransmitting in op- "together for responding to the singing of thecircuit, and means controlled by said singing responsive devices foradjusting the transmission equivalent of the circuit.

7. A; four-wire circuit comprising a pair of transmission lines fortransmitting inoposite directions, means for normally looping theends ofsaid lines together to form a circuit which will sing when the gainexceeds the loss, terminating arrangements for said lines, means wherebywhen a transmission. circuit is extended over said lines, the ends ofsaid lines will be disconnected from,

said means for looping the ends together and connected with saidterminating arrangements, devices associated with one of the means forlooping the ends of said lines together for responding to the singing ofthe circuit, and means controlled by said singing responsive devices foradjusting the transmission equivalent of the circuit, said adjustingmeans being located 'at a point along said lines intermediate betweenthe ends thereof. j

8. In a signaling system a transmission circuit whose equivalent mayvary from time to time, means associated with said circuit-forperiodically adjusting the equiva lent thereof, and .means whereby, itsaid, circuit is in use for the transmisslo-n of signals during anadjusting period, said ad justing means will not function.

9. In a signaling system a transmission circuit whose equivalent mayvary from time to time, means associated with said circuit forperiodically adjusting the equivalent thereof, and means whereb if saidcircuit is in use for the transmission of signals during an adjustingperlod, the operation of saidadjusting means will be delayed and theadjusting means will function to adjustthe'transmission equivalent ofthe circuit as soon as it is idle..

10. In a signaling system, a transmission circuit whose equivalent mayvary from time to time, means for adjusting the e uivalent of saidcircuit and means to give a busy indication when said circuit is beingadjusted. t

11. In a signalin system a" transmission circuit whose equiva ent mayvary from time to time, means for periodically adjusting the 35 meansfor looping said ends together and transmission equivalent of saidcircuit and means to give a busy indication duringthe periods when thecircuit is being adjusted to warn an operator from establishing aconnection over the said circuit. 1

12. In a signaling system a transmission circuit comprisingtwotransmission lines for transmittingin opposite directions, means forlooping the ends of said linestogether in order to adjust thetransmission equivalent thereof, terminating arrangements adaptedto beassociated with the ends of said lines, establishment of a transmissionconnection with said terminating arrangements for disconnecting the endsof the lines from the means for looping said ends together andassociating the ends of the lines with the terminating arrangements,andmeans whereby .when the transmission equivalent of the lines is beingadjusted, the operation of the means for disconnecting the ends of a thelines from' the means-for looping. the

v for transmitting 1n op ends together will be defeated.

13. In a signaling system a tranmission circuit comprising twotransmission lines osite directions,

' means for looping the on s of said lines together inorder to adjustthe transmission equivalent thereof terminatmg arrangements adapted tobe associated with the ends of said lines, means responsive to theestablishment of a transmission connection with said terminatingarrangements for disconnecting the, ends of the lines from theassociating'the ends of the lines-with the terminating arrangements, andmeans whereby when the transmission equivalent.

of the lines is being adjusted, the operation of the means fordisconnecting the ends of the lines from the means for loo ing the endstogether will be defeated, an a busy signal will be given.

14.111 a signaling system, a four-wire circuit comprising va pair oftransmission in for transmitting in opposite directions,

. i said lines,

means responsive to the,

means for looping the ends of said lines together to form a circuitwhich will sing when the gain exceeds the loss, means for adjusting thetransmission equivalent of said means functioning whenever thetransmission conditions become such that the circuit sings.

15. In a signaling system, a four-wire circuit comprising a pair oflines for transmitting in opposite directions, means for loopingthe'ends of said lines together to form a circuit which will sing whenthe gain exceeds the loss, means responsive to the singing of saidcircuit for ad usting the transmission equivalent thereof, and means socontrolled by the singing of the circuit that if the circuit beinadvertently interruptedduring the process of adjustment, the adjustingmeans will cease functioning until the circuit is againclosed, whereuponthe adjustment .of the transmission equivalent will be completed.

16. In a signaling system a four-wire circuit comprising a pair of linesfor transmittin in opposite directions, means for norma 1y looping theends of said lines-torangements to which the ends of said lines maybeconnected independently of said looping means when the lines are usedfor theitransmission of signals, means at an intermediate point alongsaid lines for adjusting the transmission equivalent thereof, said meanscomprising variable transmission devices and automatic switches forcontrolling the adjustment of said variable transmission devi es,devices associated with said means fa. looping the ends of the linestogether for responding to the singing of the circuit, and means wherebysaid devices control the operation of said automatic switches.

In testimony whereof I have signed my name to this specification this24th day of January 1921.

. OWEN H. LQYNES.

